Bottom Line:
During breaks they cooled their bodies with a cold shower and then rested in a sitting position.Diastolic pressure was reduced similarly.It can be concluded that due to high humidity and reduction of thermoregulation mechanisms, the wet sauna is more stressful for the organism than the dry sauna, where the temperature is higher with low humidity.

ABSTRACTThe aim of the paper was to follow up major physiological reactions, provoked by heat stress during dry and wet sauna baths. A physical strain index and subjective estimation of heat comfort of subjects who had not taken sauna baths before was also evaluated. Ten healthy males aged 25-28 underwent a dry sauna bath and then after a one-month break they underwent a steam sauna bath. Each time, they entered the sauna chamber 3 times for 15 minutes with five-minute breaks. During breaks they cooled their bodies with a cold shower and then rested in a sitting position. Before and after the baths, body mass and blood pressure were measured. Rectal temperature and heart rate were monitored during the baths. The physiological strain index (PSI) and cumulative heat strain index (CHSI) were calculated. Subjects assessed heat comfort by Bedford's scale. Greater body mass losses were observed after the dry sauna bath compared to the wet sauna (-0.72 vs. -0.36 kg respectively). However, larger increases in rectal temperature and heart rate were observed during the wet sauna bath (38.8% and 21.2% respectively). Both types of sauna baths caused elevation of systolic blood pressure, but changes were greater after the dry one. Diastolic pressure was reduced similarly. Subjective feelings of heat comfort as well as PSI (4.83 ± 0.29 vs. 5.7 ± 0.28) and CHSI (76.3 ± 18.4 vs. 144.6 ± 21.7) were greater during the wet sauna bath. It can be concluded that due to high humidity and reduction of thermoregulation mechanisms, the wet sauna is more stressful for the organism than the dry sauna, where the temperature is higher with low humidity. Both observed indexes (PSI and CHSI) could be appropriate for objective assessment of heat strain during passive heating of the organism.

Mentions:
Body mass changes caused by hyperthermia are presented in Table 1. In the examined groups average body mass loss was 0.72 kg after dry sauna and 0.36 after wet sauna bath. Both changes were statistically significant (p<0.01). Body mass loss was two times higher after dry sauna than after wet one (p<0.05). Rectal temperature increased by 1.16°C after dry (p<0.01) and by 1.61°C after wet sauna (p<0.01) (Table 1; Fig. 1). The increase of the rectal temperature was higher during the bath in the wet sauna in comparison to the dry one (p<0.01) (Fig. 1). During both baths (dry and wet) the HR increased by 59.4 and 72 beats·min-1 respectively (p<0.01). The systolic blood pressure increased by 20 mmHg (p<0.01) during the dry, and by 17.7 mmHg (p<0.05) in the wet sauna (Table 1). Diastolic pressure decreased by 15 mmHg (p<0.01) in the dry, and by 20 mmHg (p<0.01) in the wet sauna (p<0.01). The increase of systolic pressure was higher during the dry sauna bath (p<0.05), whereas the diastolic pressure decreased more during the wet sauna (p<0.01). The subjective estimation of heat comfort (Bedford's scale) indicates that the heat discomfort is greater in the wet sauna especially during the last phase of exposure (Fig. 2). The physiological strain index (PSI) and cumulative heat strain index (CHSI) were also greater during the wet sauna session (Fig. 3; Table 1). Significant differences were observed from the first entrance in the PSI index and from the second entrance in the CHSI index (Fig. 3). In both baths indexes were significantly correlated during all entrances with each other (r=0.87). With Bedford's scale indexes were significantly correlated only for the third entrance (r=0.64 for PSI; r=0.54 for CHSI).

Mentions:
Body mass changes caused by hyperthermia are presented in Table 1. In the examined groups average body mass loss was 0.72 kg after dry sauna and 0.36 after wet sauna bath. Both changes were statistically significant (p<0.01). Body mass loss was two times higher after dry sauna than after wet one (p<0.05). Rectal temperature increased by 1.16°C after dry (p<0.01) and by 1.61°C after wet sauna (p<0.01) (Table 1; Fig. 1). The increase of the rectal temperature was higher during the bath in the wet sauna in comparison to the dry one (p<0.01) (Fig. 1). During both baths (dry and wet) the HR increased by 59.4 and 72 beats·min-1 respectively (p<0.01). The systolic blood pressure increased by 20 mmHg (p<0.01) during the dry, and by 17.7 mmHg (p<0.05) in the wet sauna (Table 1). Diastolic pressure decreased by 15 mmHg (p<0.01) in the dry, and by 20 mmHg (p<0.01) in the wet sauna (p<0.01). The increase of systolic pressure was higher during the dry sauna bath (p<0.05), whereas the diastolic pressure decreased more during the wet sauna (p<0.01). The subjective estimation of heat comfort (Bedford's scale) indicates that the heat discomfort is greater in the wet sauna especially during the last phase of exposure (Fig. 2). The physiological strain index (PSI) and cumulative heat strain index (CHSI) were also greater during the wet sauna session (Fig. 3; Table 1). Significant differences were observed from the first entrance in the PSI index and from the second entrance in the CHSI index (Fig. 3). In both baths indexes were significantly correlated during all entrances with each other (r=0.87). With Bedford's scale indexes were significantly correlated only for the third entrance (r=0.64 for PSI; r=0.54 for CHSI).

Bottom Line:
During breaks they cooled their bodies with a cold shower and then rested in a sitting position.Diastolic pressure was reduced similarly.It can be concluded that due to high humidity and reduction of thermoregulation mechanisms, the wet sauna is more stressful for the organism than the dry sauna, where the temperature is higher with low humidity.

ABSTRACTThe aim of the paper was to follow up major physiological reactions, provoked by heat stress during dry and wet sauna baths. A physical strain index and subjective estimation of heat comfort of subjects who had not taken sauna baths before was also evaluated. Ten healthy males aged 25-28 underwent a dry sauna bath and then after a one-month break they underwent a steam sauna bath. Each time, they entered the sauna chamber 3 times for 15 minutes with five-minute breaks. During breaks they cooled their bodies with a cold shower and then rested in a sitting position. Before and after the baths, body mass and blood pressure were measured. Rectal temperature and heart rate were monitored during the baths. The physiological strain index (PSI) and cumulative heat strain index (CHSI) were calculated. Subjects assessed heat comfort by Bedford's scale. Greater body mass losses were observed after the dry sauna bath compared to the wet sauna (-0.72 vs. -0.36 kg respectively). However, larger increases in rectal temperature and heart rate were observed during the wet sauna bath (38.8% and 21.2% respectively). Both types of sauna baths caused elevation of systolic blood pressure, but changes were greater after the dry one. Diastolic pressure was reduced similarly. Subjective feelings of heat comfort as well as PSI (4.83 ± 0.29 vs. 5.7 ± 0.28) and CHSI (76.3 ± 18.4 vs. 144.6 ± 21.7) were greater during the wet sauna bath. It can be concluded that due to high humidity and reduction of thermoregulation mechanisms, the wet sauna is more stressful for the organism than the dry sauna, where the temperature is higher with low humidity. Both observed indexes (PSI and CHSI) could be appropriate for objective assessment of heat strain during passive heating of the organism.